Flexible functional materials can be used to tune and efficiently control how mechanical information can be detected and transferred in a biomimetic sensor design. Developments in thin-film-based MEMS (Micro-Electro-Mechanical Systems) have enabled the cost-effective manufacture of these flexible functional materials. These flexible elements can be, for example, cantilever beams, membranes, and bridges that are suspended over a base layer. Additional layers are added to the base using appropriate deposition techniques to create a controllable stress gradient across the layered structure. On release, the stress gradient creates “out-of-plane” architectures, such as upwards-bent cantilevers or dome-shaped membranes, yielding mechanical devices that are sensitive to normal and shear forces. Such MEMS can be sensitive to environmental changes in tactile, pressure, and flow characteristics.
Traditionally, two methods have been employed to manufacture MEMS. On the one hand, dry etch techniques using chlorine based chemistries and reactive ion etching are the most prevalent. However, these typically require the use of very reactive and toxic gases and the use of specialized equipment, which necessitate implementation of complex systems and capital intensive investments in order to meet desired capabilities while also meeting stringent safety requirements. As such, dry etch suffers from not only high initial investment costs, but also relatively low throughput capabilities. On the other hand, wet etch techniques suffer from inconsistent etch rates for some materials. As such, previous techniques have not provided a way to reliably pattern those materials.